eye anatomy

Eye Anatomy
Parts of the Eye

The eye is a complex organ. How well we see depends on how each part functions as well as how all the components work together.

How The Eye Works

  1. Light enters the eye through the cornea, the transparent convex lens that covers the iris and the pupil.
  2. The iris is the colored part of the eye that sits behind the cornea. It is a circular muscle that regulated the amount of light entering the eye. The opening in the iris is called the pupil.
  3. Behind the iris is the crystalline lens, which focuses the light to the back of the eye. With the help of the ciliary muscle, the lens changes shape to focus on near or distant objects.
  4. The light then travels through a transparent gel, called the vitreous humor (fills the eye ball and gives it its shape) and reaches the back of the eye.
  5. The back of the eye is covered with a thin light sensitive lining called the retina, which produces visual information. The central area of the retina is the macula, which provides the clearest vision.
  6. This visual information is carried to the brain through the optic nerve, where it is interpreted into a visual picture

How Does Aging Affect Eye Anatomy?

As we age, nearly all parts of the eye are affected. The rate at which vision declines varies depending on lifestyle, environment and genetics. The aging process actually begins in the 20's but a change is not felt by most until we reach our 40's.

What was once an effortless task for most of us, takes more concentration. Visual perception slows down and so does the ability of the eye to function.

Most baby boomer women have already experienced changes in vision. Some changes though, may cause such a slow decline that you may not notice that your eye sight has become impaired. It is therefore, very important that you go to your eye doctor regularly for a checkup, even if you feel your vision is fine.

Presbyopia is the inability of the eye to focus on objects that are nearby. It appears around age 40 plus and is a normal effect of aging. Whether you wore glasses for distance vision or always had 20 20 vision, you will begin to notice a change when reading or doing any type of close up work. Vision will become blurry or if you wear glasses for myopia, you will find that your close up vision improves when you remove your glasses.

The crystalline lens and ciliary muscle lose their flexibility, making it harder to focus up close. Holding the object or book at a further distance can help you see it more clearly, but eventually your arm will not be long enough and you will need reading glasses. They can be purchased over the counter or be custom fitted by an optometrist.

Cataract is the clouding over of the crystalline lens of your eyes. Symptoms include blurry vision, faded colors, double vision, and difficulty seeing at night. Most cataracts develop slowly and eventually interfere with vision so much that no amount of lighting or eye glasses can correct it. It doesn't usually cause any kind of irritation or pain. Cataract is a normal part of aging and is not considered a disease. It is highly treatable through a short uncomplicated surgical procedure.

Smaller pupils. As we age the muscles of the iris lose strength. The pupils become smaller and their reaction to light and dark becomes slower. Objects may appear to be less bright and sudden changes from dark to light or light to dark may be very bothersome. Adding more lighting around the home is one way to compensate for this change.

Reduced peripheral vision. As you age you might have to turn your head more to see to the sides. The size of our visual field decreases as we get older and can decrease by 30% by the time we reach our 80's.

Decline in color sensitivity. The ability to distinguish between pastel colors is also reduced with age. Blue and green become more difficult to see than red, yellow and orange. The retina is responsible for normal color vision, but with age it loses its sensitivity and colors begin to look washed out.

Dry eyes . As we approach our 50's, we produce less tears. It can make eyes feel tired and cause burning, tearing and other uncomfortable sensations.


Age-related eye diseases

Glaucoma is a group of diseases that affect the optic nerve. If left untreated it can lead to permanent damage causing a loss in peripheral vision, and can progress to blindness. It has been called the "sneak thief of sight" because it occurs slowly over a long period of time and is often only detected when it is very advanced. It is the second leading cause of blindness worldwide.

Age-Related Macular Degeneration (AMD) gradually destroys sharp, central vision. AMD affects the macula, which is the part of the eye that allows us to see fine details. AMD can make it very difficult to read or recognize faces, but peripheral vision remains unharmed.

Diabetic retinopathy is a complication of diabetes that results from damage to the blood vessels in the retina. It can cause severe vision loss or even blindness.


Other eye issues

Eye twitching – Common causes of eye twitching are eye strain, fatigue, lack of sleep, stress, and too much caffeine. If it's accompanied by other symptoms, you should have a checkup. Eye twitching is very common among the general population, especially women over 60. It can last for weeks or months, but is not usually considered a serious problem. Lack of certain vitamins, too much alcohol, overuse of the computer and dry eyes can also cause twitching. Another form of twitching called blepharospasm, involves involuntary spasm and closing of the eye lid and is caused by a neurological condition. If your twitching persists, see a doctor.

Eye floaters - Floaters in the eye are those spots, strands, or specks you sometimes see moving around in your eyes.

Pinkeye - Also called conjunctivitis, pinkeye is an eye infection that can be viral, bacterial or allergy related. It can occur at any age, but the elderly are more susceptible.

Tired eyes - Sitting in front of the computer for long hours is one of the major causes of tired eyes, and so is stress. But there are a multitude of other reasons for your eyes feeling tired; lack of sleep, allergies, pollutants in the air, lack of vitamins, or straining to see with glasses that need a new prescription. To relieve tired eyes, lean back or lie down for 15-20 minutes, close your eyes and r-e-e-e-l-a-a-x. While you're there, place couple of slices of cold cucumber on your eyelids. They help reduce puffiness and irritated eyes. Prepare plenty of slices and change them as they warm up.


Do you know the difference between an Ophthalmologist, an Optometrist and an Optician? Learn about your Vision Professionals before your next check-up.


You Can Protect Your Eyesight provides information you can use to prevent injuries, illnesses and learn first aid. Prepare for anything that does happen to your eyesight. Learn about your Eyes and it will help you live a better life.


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